1. Field of the Invention
The present invention relates to a wire electric discharge machining apparatus in which the machining outline can be checked.
2. Description of the Prior Art
In machining with a wire electric discharge machining apparatus, a plurality of machining shapes are typically machined based on a single machining program. When multiple machining operations are thus conducted on a plurality of machining shapes, the process from the initiation of machining program execution to completion of machining according to this machining program takes a long time and the wire electric discharge machining apparatus is usually operated in an automatic mode, for example, in the nighttime.
When a plurality of machining shapes are machined with a single machining program, as described above, the machining takes a long time and is usually conducted in an automatic operation mode of a wire electric discharge machining apparatus. For this reason, it remains unclear how many machining shapes are to be machined or how many times the machining (rough machining, finish machining) of a single machining shape is to be conducted. Machining is conducted in an automatic mode in the nighttime and the machining progress state is first verified by viewing the machining state in the morning. Therefore, the machining end is difficult to predict when the machining is started.
There are also cases in which the machining shapes which presently require no machining are programmed in the machining program or an unnecessary large number of finish machining operation are programmed. However, the machining outline that has thus been programmed cannot be clarified in advance. Furthermore, it is sometimes desirable to machine urgently only a certain machining shape that has been programmed in a machining program, but to select and machine this shape is difficult. Moreover, a machining starting hole has to be machined in advance for each machining shape in order to conduct machining of a plurality of machining shapes. However, in a case where machining starting hole is forgotten to be machined on a workpiece or a machining starting hole is machined on a workpiece in a wrong position, and such a workpiece is set in a wire electric discharge machining apparatus and then an automatic nighttime operation is started, expecting the machining of the workpiece to be completed in the next morning, there may be cases in which no machining is conducted and subsequent operations are impeded.